/*
 *********************************************************************************************************
 *                                                uC/OS-II
 *                                          The Real-Time Kernel
 *                                  MUTUAL EXCLUSION SEMAPHORE MANAGEMENT
 *
 *                          (c) Copyright 1992-2006, Jean J. Labrosse, Weston, FL
 *                                           All Rights Reserved
 *
 * File    : OS_MUTEX.C
 * By      : Jean J. Labrosse
 * Version : V2.83
 *********************************************************************************************************
 */

#ifndef  OS_MASTER_FILE
#include <ucos_ii.h>
#endif


#if OS_MUTEX_EN > 0
/*
 *********************************************************************************************************
 *                                            LOCAL CONSTANTS
 *********************************************************************************************************
 */

#define  OS_MUTEX_KEEP_LOWER_8   0x00FFu
#define  OS_MUTEX_KEEP_UPPER_8   0xFF00u

#define  OS_MUTEX_AVAILABLE      0x00FFu

/*
 *********************************************************************************************************
 *                                            LOCAL CONSTANTS
 *********************************************************************************************************
 */

static void  OSMutex_RdyAtPrio(OS_TCB *ptcb, INT8U prio);

/*$PAGE*/
/*
 *********************************************************************************************************
 *                                   ACCEPT MUTUAL EXCLUSION SEMAPHORE
 *
 * Description: This  function checks the mutual exclusion semaphore to see if a resource is available.
 *              Unlike OSMutexPend(), OSMutexAccept() does not suspend the calling task if the resource is
 *              not available or the event did not occur.
 *
 * Arguments  : pevent     is a pointer to the event control block
 *
 *              err        is a pointer to an error code which will be returned to your application:
 *                            OS_NO_ERR          if the call was successful.
 *                            OS_ERR_EVENT_TYPE  if 'pevent' is not a pointer to a mutex
 *                            OS_ERR_PEVENT_NULL 'pevent' is a NULL pointer
 *                            OS_ERR_PEND_ISR     if you called this function from an ISR
 *                            OS_ERR_PIP_LOWER    If the priority of the task that owns the Mutex is
 *                                                HIGHER (i.e. a lower number) than the PIP.  This error
 *                                                indicates that you did not set the PIP higher (lower
 *                                                number) than ALL the tasks that compete for the Mutex.
 *                                                Unfortunately, this is something that could not be
 *                                                detected when the Mutex is created because we don't know
 *                                                what tasks will be using the Mutex.
 *
 * Returns    : == 1       if the resource is available, the mutual exclusion semaphore is acquired
 *              == 0       a) if the resource is not available
 *                         b) you didn't pass a pointer to a mutual exclusion semaphore
 *                         c) you called this function from an ISR
 *
 * Warning(s) : This function CANNOT be called from an ISR because mutual exclusion semaphores are
 *              intended to be used by tasks only.
 *********************************************************************************************************
 */

#if OS_MUTEX_ACCEPT_EN > 0
INT8U  OSMutexAccept(OS_EVENT *pevent, INT8U *err)
{
    INT8U pip;                                         /* Priority Inheritance Priority (PIP)          */

#if OS_CRITICAL_METHOD == 3                            /* Allocate storage for CPU status register     */
    OS_CPU_SR cpu_sr = 0;
#endif



#if OS_ARG_CHK_EN > 0
    if (err == (INT8U*)0)                              /* Validate 'err'                               */
    {
        return 0;
    }
    if (pevent == (OS_EVENT*)0)                        /* Validate 'pevent'                            */
    {
        *err = OS_ERR_PEVENT_NULL;
        return 0;
    }
#endif
    if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX)    /* Validate event block type                    */
    {
        *err = OS_ERR_EVENT_TYPE;
        return 0;
    }
    if (OSIntNesting > 0)                              /* Make sure it's not called from an ISR        */
    {
        *err = OS_ERR_PEND_ISR;
        return 0;
    }
    OS_ENTER_CRITICAL();                               /* Get value (0 or 1) of Mutex                  */
    pip = (INT8U)(pevent->OSEventCnt >> 8);            /* Get PIP from mutex                           */
    if ((pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8) == OS_MUTEX_AVAILABLE)
    {
        pevent->OSEventCnt &= OS_MUTEX_KEEP_UPPER_8;   /*      Mask off LSByte (Acquire Mutex)         */
        pevent->OSEventCnt |= OSTCBCur->OSTCBPrio;     /*      Save current task priority in LSByte    */
        pevent->OSEventPtr  = (void*)OSTCBCur;         /*      Link TCB of task owning Mutex           */
        if (OSTCBCur->OSTCBPrio <= pip)                /*      PIP 'must' have a SMALLER prio ...      */
        {
            OS_EXIT_CRITICAL();                        /*      ... than current task!                  */
            *err  = OS_ERR_PIP_LOWER;
        }
        else
        {
            OS_EXIT_CRITICAL();
            *err  = OS_NO_ERR;
        }
        return 1;
    }
    OS_EXIT_CRITICAL();
    *err = OS_NO_ERR;
    return 0;
}
#endif

/*$PAGE*/
/*
 *********************************************************************************************************
 *                                  CREATE A MUTUAL EXCLUSION SEMAPHORE
 *
 * Description: This function creates a mutual exclusion semaphore.
 *
 * Arguments  : prio          is the priority to use when accessing the mutual exclusion semaphore.  In
 *                            other words, when the semaphore is acquired and a higher priority task
 *                            attempts to obtain the semaphore then the priority of the task owning the
 *                            semaphore is raised to this priority.  It is assumed that you will specify
 *                            a priority that is LOWER in value than ANY of the tasks competing for the
 *                            mutex.
 *
 *              err           is a pointer to an error code which will be returned to your application:
 *                               OS_NO_ERR           if the call was successful.
 *                               OS_ERR_CREATE_ISR   if you attempted to create a MUTEX from an ISR
 *                               OS_PRIO_EXIST       if a task at the priority inheritance priority
 *                                                   already exist.
 *                               OS_ERR_PEVENT_NULL  No more event control blocks available.
 *                               OS_PRIO_INVALID     if the priority you specify is higher that the
 *                                                   maximum allowed (i.e. > OS_LOWEST_PRIO)
 *
 * Returns    : != (void *)0  is a pointer to the event control clock (OS_EVENT) associated with the
 *                            created mutex.
 *              == (void *)0  if an error is detected.
 *
 * Note(s)    : 1) The LEAST significant 8 bits of '.OSEventCnt' are used to hold the priority number
 *                 of the task owning the mutex or 0xFF if no task owns the mutex.
 *
 *              2) The MOST  significant 8 bits of '.OSEventCnt' are used to hold the priority number
 *                 to use to reduce priority inversion.
 *********************************************************************************************************
 */

OS_EVENT  *OSMutexCreate(INT8U prio, INT8U *err)
{
    OS_EVENT  *pevent;

#if OS_CRITICAL_METHOD == 3                                /* Allocate storage for CPU status register */
    OS_CPU_SR cpu_sr = 0;
#endif



#if OS_ARG_CHK_EN > 0
    if (err == (INT8U*)0)                                  /* Validate 'err'                           */
    {
        return (OS_EVENT*)0;
    }
    if (prio >= OS_LOWEST_PRIO)                            /* Validate PIP                             */
    {
        *err = OS_PRIO_INVALID;
        return (OS_EVENT*)0;
    }
#endif
    if (OSIntNesting > 0)                                  /* See if called from ISR ...               */
    {
        *err = OS_ERR_CREATE_ISR;                          /* ... can't CREATE mutex from an ISR       */
        return (OS_EVENT*)0;
    }
    OS_ENTER_CRITICAL();
    if (OSTCBPrioTbl[prio] != (OS_TCB*)0)                  /* Mutex priority must not already exist    */
    {
        OS_EXIT_CRITICAL();                                /* Task already exist at priority ...       */
        *err = OS_PRIO_EXIST;                              /* ... inheritance priority                 */
        return (OS_EVENT*)0;
    }
    OSTCBPrioTbl[prio] = (OS_TCB*)1;                       /* Reserve the table entry                  */
    pevent             = OSEventFreeList;                  /* Get next free event control block        */
    if (pevent == (OS_EVENT*)0)                            /* See if an ECB was available              */
    {
        OSTCBPrioTbl[prio] = (OS_TCB*)0;                   /* No, Release the table entry              */
        OS_EXIT_CRITICAL();
        *err               = OS_ERR_PEVENT_NULL;           /* No more event control blocks             */
        return pevent;
    }
    OSEventFreeList        = (OS_EVENT*)OSEventFreeList->OSEventPtr;    /* Adjust the free list        */
    OS_EXIT_CRITICAL();
    pevent->OSEventType    = OS_EVENT_TYPE_MUTEX;
    pevent->OSEventCnt     = (INT16U)((INT16U)prio << 8) | OS_MUTEX_AVAILABLE; /* Resource is avail.   */
    pevent->OSEventPtr     = (void*)0;                                  /* No task owning the mutex    */
#if OS_EVENT_NAME_SIZE > 1
    pevent->OSEventName[0] = '?';
    pevent->OSEventName[1] = OS_ASCII_NUL;
#endif
    OS_EventWaitListInit(pevent);
    *err                   = OS_NO_ERR;
    return pevent;
}

/*$PAGE*/
/*
 *********************************************************************************************************
 *                                          DELETE A MUTEX
 *
 * Description: This function deletes a mutual exclusion semaphore and readies all tasks pending on the it.
 *
 * Arguments  : pevent        is a pointer to the event control block associated with the desired mutex.
 *
 *              opt           determines delete options as follows:
 *                            opt == OS_DEL_NO_PEND   Delete mutex ONLY if no task pending
 *                            opt == OS_DEL_ALWAYS    Deletes the mutex even if tasks are waiting.
 *                                                    In this case, all the tasks pending will be readied.
 *
 *              err           is a pointer to an error code that can contain one of the following values:
 *                            OS_NO_ERR               The call was successful and the mutex was deleted
 *                            OS_ERR_DEL_ISR          If you attempted to delete the MUTEX from an ISR
 *                            OS_ERR_INVALID_OPT      An invalid option was specified
 *                            OS_ERR_TASK_WAITING     One or more tasks were waiting on the mutex
 *                            OS_ERR_EVENT_TYPE       If you didn't pass a pointer to a mutex
 *                            OS_ERR_PEVENT_NULL      If 'pevent' is a NULL pointer.
 *
 * Returns    : pevent        upon error
 *              (OS_EVENT *)0 if the mutex was successfully deleted.
 *
 * Note(s)    : 1) This function must be used with care.  Tasks that would normally expect the presence of
 *                 the mutex MUST check the return code of OSMutexPend().
 *
 *              2) This call can potentially disable interrupts for a long time.  The interrupt disable
 *                 time is directly proportional to the number of tasks waiting on the mutex.
 *
 *              3) Because ALL tasks pending on the mutex will be readied, you MUST be careful because the
 *                 resource(s) will no longer be guarded by the mutex.
 *
 *              4) IMPORTANT: In the 'OS_DEL_ALWAYS' case, we assume that the owner of the Mutex (if there
 *                            is one) is ready-to-run and is thus NOT pending on another kernel object or
 *                            has delayed itself.  In other words, if a task owns the mutex being deleted,
 *                            that task will be made ready-to-run at its original priority.
 *********************************************************************************************************
 */

#if OS_MUTEX_DEL_EN
OS_EVENT  *OSMutexDel(OS_EVENT *pevent, INT8U opt, INT8U *err)
{
    BOOLEAN tasks_waiting;
    OS_EVENT  *pevent_return;
    INT8U pip;                                             /* Priority inheritance priority            */
    INT8U prio;
    OS_TCB    *ptcb;

#if OS_CRITICAL_METHOD == 3                                /* Allocate storage for CPU status register */
    OS_CPU_SR cpu_sr = 0;
#endif



#if OS_ARG_CHK_EN > 0
    if (err == (INT8U*)0)                                  /* Validate 'err'                           */
    {
        return (OS_EVENT*)0;
    }
    if (pevent == (OS_EVENT*)0)                            /* Validate 'pevent'                        */
    {
        *err = OS_ERR_PEVENT_NULL;
        return (OS_EVENT*)0;
    }
#endif
    if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX)        /* Validate event block type                */
    {
        *err = OS_ERR_EVENT_TYPE;
        return pevent;
    }
    if (OSIntNesting > 0)                                  /* See if called from ISR ...               */
    {
        *err = OS_ERR_DEL_ISR;                             /* ... can't DELETE from an ISR             */
        return pevent;
    }
    OS_ENTER_CRITICAL();
    if (pevent->OSEventGrp != 0)                           /* See if any tasks waiting on mutex        */
    {
        tasks_waiting = OS_TRUE;                           /* Yes                                      */
    }
    else
    {
        tasks_waiting = OS_FALSE;                          /* No                                       */
    }
    switch (opt)
    {
    case OS_DEL_NO_PEND:                                   /* DELETE MUTEX ONLY IF NO TASK WAITING --- */
        if (tasks_waiting == OS_FALSE)
        {
#if OS_EVENT_NAME_SIZE > 1
            pevent->OSEventName[0] = '?';                  /* Unknown name                             */
            pevent->OSEventName[1] = OS_ASCII_NUL;
#endif
            pip                 = (INT8U)(pevent->OSEventCnt >> 8);
            OSTCBPrioTbl[pip]   = (OS_TCB*)0;              /* Free up the PIP                          */
            pevent->OSEventType = OS_EVENT_TYPE_UNUSED;
            pevent->OSEventPtr  = OSEventFreeList;         /* Return Event Control Block to free list  */
            pevent->OSEventCnt  = 0;
            OSEventFreeList     = pevent;
            OS_EXIT_CRITICAL();
            *err                = OS_NO_ERR;
            pevent_return       = (OS_EVENT*)0;            /* Mutex has been deleted                   */
        }
        else
        {
            OS_EXIT_CRITICAL();
            *err                = OS_ERR_TASK_WAITING;
            pevent_return       = pevent;
        }
        break;

    case OS_DEL_ALWAYS:                                    /* ALWAYS DELETE THE MUTEX ---------------- */
        pip  = (INT8U)(pevent->OSEventCnt >> 8);                          /* Get PIP of mutex          */
        prio = (INT8U)(pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8);       /* Get owner's original prio */
        ptcb = (OS_TCB*)pevent->OSEventPtr;
        if (ptcb != (OS_TCB*)0)                            /* See if any task owns the mutex           */
        {
            if (ptcb->OSTCBPrio == pip)                    /* See if original prio was changed         */
            {
                OSMutex_RdyAtPrio(ptcb, prio);             /* Yes, Restore the task's original prio    */
            }
        }
        while (pevent->OSEventGrp != 0)                    /* Ready ALL tasks waiting for mutex        */
        {
            (void)OS_EventTaskRdy(pevent, (void*)0, OS_STAT_MUTEX);
        }
#if OS_EVENT_NAME_SIZE > 1
        pevent->OSEventName[0] = '?';                      /* Unknown name                             */
        pevent->OSEventName[1] = OS_ASCII_NUL;
#endif
        pip                 = (INT8U)(pevent->OSEventCnt >> 8);
        OSTCBPrioTbl[pip]   = (OS_TCB*)0;                  /* Free up the PIP                          */
        pevent->OSEventType = OS_EVENT_TYPE_UNUSED;
        pevent->OSEventPtr  = OSEventFreeList;             /* Return Event Control Block to free list  */
        pevent->OSEventCnt  = 0;
        OSEventFreeList     = pevent;                      /* Get next free event control block        */
        OS_EXIT_CRITICAL();
        if (tasks_waiting == OS_TRUE)                      /* Reschedule only if task(s) were waiting  */
        {
            OS_Sched();                                    /* Find highest priority task ready to run  */
        }
        *err          = OS_NO_ERR;
        pevent_return = (OS_EVENT*)0;                      /* Mutex has been deleted                   */
        break;

    default:
        OS_EXIT_CRITICAL();
        *err          = OS_ERR_INVALID_OPT;
        pevent_return = pevent;
        break;
    }
    return pevent_return;
}
#endif

/*$PAGE*/
/*
 *********************************************************************************************************
 *                                  PEND ON MUTUAL EXCLUSION SEMAPHORE
 *
 * Description: This function waits for a mutual exclusion semaphore.
 *
 * Arguments  : pevent        is a pointer to the event control block associated with the desired
 *                            mutex.
 *
 *              timeout       is an optional timeout period (in clock ticks).  If non-zero, your task will
 *                            wait for the resource up to the amount of time specified by this argument.
 *                            If you specify 0, however, your task will wait forever at the specified
 *                            mutex or, until the resource becomes available.
 *
 *              err           is a pointer to where an error message will be deposited.  Possible error
 *                            messages are:
 *                               OS_NO_ERR          The call was successful and your task owns the mutex
 *                               OS_TIMEOUT         The mutex was not available within the specified time.
 *                               OS_ERR_EVENT_TYPE  If you didn't pass a pointer to a mutex
 *                               OS_ERR_PEVENT_NULL 'pevent' is a NULL pointer
 *                               OS_ERR_PEND_ISR    If you called this function from an ISR and the result
 *                                                  would lead to a suspension.
 *                               OS_ERR_PIP_LOWER   If the priority of the task that owns the Mutex is
 *                                                  HIGHER (i.e. a lower number) than the PIP.  This error
 *                                                  indicates that you did not set the PIP higher (lower
 *                                                  number) than ALL the tasks that compete for the Mutex.
 *                                                  Unfortunately, this is something that could not be
 *                                                  detected when the Mutex is created because we don't know
 *                                                  what tasks will be using the Mutex.
 *
 * Returns    : none
 *
 * Note(s)    : 1) The task that owns the Mutex MUST NOT pend on any other event while it owns the mutex.
 *
 *              2) You MUST NOT change the priority of the task that owns the mutex
 *********************************************************************************************************
 */
void  OSMutexPend(OS_EVENT *pevent, INT16U timeout, INT8U *err)
{
    INT8U pip;                                             /* Priority Inheritance Priority (PIP)      */
    INT8U mprio;                                           /* Mutex owner priority                     */
    BOOLEAN rdy;                                           /* Flag indicating task was ready           */
    OS_TCB    *ptcb;
    OS_EVENT  *pevent2;
    INT8U y;

#if OS_CRITICAL_METHOD == 3                                /* Allocate storage for CPU status register */
    OS_CPU_SR cpu_sr = 0;
#endif



#if OS_ARG_CHK_EN > 0
    if (err == (INT8U*)0)                                  /* Validate 'err'                           */
    {
        return;
    }
    if (pevent == (OS_EVENT*)0)                            /* Validate 'pevent'                        */
    {
        *err = OS_ERR_PEVENT_NULL;
        return;
    }
#endif
    if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX)        /* Validate event block type                */
    {
        *err = OS_ERR_EVENT_TYPE;
        return;
    }
    if (OSIntNesting > 0)                                  /* See if called from ISR ...               */
    {
        *err = OS_ERR_PEND_ISR;                            /* ... can't PEND from an ISR               */
        return;
    }
    if (OSLockNesting > 0)                                 /* See if called with scheduler locked ...  */
    {
        *err = OS_ERR_PEND_LOCKED;                         /* ... can't PEND when locked               */
        return;
    }
    OS_ENTER_CRITICAL();
    pip = (INT8U)(pevent->OSEventCnt >> 8);                /* Get PIP from mutex                       */
                                                           /* Is Mutex available?                      */
    if ((INT8U)(pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8) == OS_MUTEX_AVAILABLE)
    {
        pevent->OSEventCnt &= OS_MUTEX_KEEP_UPPER_8;       /* Yes, Acquire the resource                */
        pevent->OSEventCnt |= OSTCBCur->OSTCBPrio;         /*      Save priority of owning task        */
        pevent->OSEventPtr  = (void*)OSTCBCur;             /*      Point to owning task's OS_TCB       */
        if (OSTCBCur->OSTCBPrio <= pip)                    /*      PIP 'must' have a SMALLER prio ...  */
        {
            OS_EXIT_CRITICAL();                            /*      ... than current task!              */
            *err  = OS_ERR_PIP_LOWER;
        }
        else
        {
            OS_EXIT_CRITICAL();
            *err  = OS_NO_ERR;
        }
        return;
    }
    mprio = (INT8U)(pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8);  /* No, Get priority of mutex owner   */
    ptcb  = (OS_TCB*)(pevent->OSEventPtr);                        /*     Point to TCB of mutex owner   */
    if (ptcb->OSTCBPrio > pip)                                    /*     Need to promote prio of owner?*/
    {
        if (mprio > OSTCBCur->OSTCBPrio)
        {
            y = ptcb->OSTCBY;
            if ((OSRdyTbl[y] & ptcb->OSTCBBitX) != 0)             /*     See if mutex owner is ready   */
            {
                OSRdyTbl[y] &= ~ptcb->OSTCBBitX;                  /*     Yes, Remove owner from Rdy ...*/
                if (OSRdyTbl[y] == 0)                             /*          ... list at current prio */
                {
                    OSRdyGrp &= ~ptcb->OSTCBBitY;
                }
                rdy = OS_TRUE;
            }
            else
            {
                pevent2 = ptcb->OSTCBEventPtr;
                if (pevent2 != (OS_EVENT*)0)                      /* Remove from event wait list       */
                {
                    if ((pevent2->OSEventTbl[ptcb->OSTCBY] &= ~ptcb->OSTCBBitX) == 0)
                    {
                        pevent2->OSEventGrp &= ~ptcb->OSTCBBitY;
                    }
                }
                rdy = OS_FALSE;                            /* No                                       */
            }
            ptcb->OSTCBPrio = pip;                         /* Change owner task prio to PIP            */
#if OS_LOWEST_PRIO <= 63
            ptcb->OSTCBY    = (INT8U)( ptcb->OSTCBPrio >> 3);
            ptcb->OSTCBX    = (INT8U)( ptcb->OSTCBPrio & 0x07);
            ptcb->OSTCBBitY = (INT8U)(1 << ptcb->OSTCBY);
            ptcb->OSTCBBitX = (INT8U)(1 << ptcb->OSTCBX);
#else
            ptcb->OSTCBY    = (INT8U)((ptcb->OSTCBPrio >> 4) & 0xFF);
            ptcb->OSTCBX    = (INT8U)( ptcb->OSTCBPrio & 0x0F);
            ptcb->OSTCBBitY = (INT16U)(1 << ptcb->OSTCBY);
            ptcb->OSTCBBitX = (INT16U)(1 << ptcb->OSTCBX);
#endif
            if (rdy == OS_TRUE)                            /* If task was ready at owner's priority ...*/
            {
                OSRdyGrp               |= ptcb->OSTCBBitY; /* ... make it ready at new priority.       */
                OSRdyTbl[ptcb->OSTCBY] |= ptcb->OSTCBBitX;
            }
            else
            {
                pevent2 = ptcb->OSTCBEventPtr;
                if (pevent2 != (OS_EVENT*)0)               /* Remove from event wait list              */
                {
                    pevent2->OSEventGrp               |= ptcb->OSTCBBitY;
                    pevent2->OSEventTbl[ptcb->OSTCBY] |= ptcb->OSTCBBitX;
                }
            }
            OSTCBPrioTbl[pip] = ptcb;
        }
    }
    OSTCBCur->OSTCBStat   |= OS_STAT_MUTEX;           /* Mutex not available, pend current task        */
    OSTCBCur->OSTCBPendTO  = OS_FALSE;
    OSTCBCur->OSTCBDly     = timeout;                 /* Store timeout in current task's TCB           */
    OS_EventTaskWait(pevent);                         /* Suspend task until event or timeout occurs    */
    OS_EXIT_CRITICAL();
    OS_Sched();                                       /* Find next highest priority task ready         */
    OS_ENTER_CRITICAL();
    if (OSTCBCur->OSTCBPendTO == OS_TRUE)             /* See if we timed out during the pend           */
    {
        OS_EventTO(pevent);
        OS_EXIT_CRITICAL();
        *err = OS_TIMEOUT;                            /* Indicate that we didn't get mutex within TO   */
        return;
    }
    OSTCBCur->OSTCBEventPtr = (OS_EVENT*)0;
    OS_EXIT_CRITICAL();
    *err = OS_NO_ERR;
}
/*$PAGE*/
/*
 *********************************************************************************************************
 *                                  POST TO A MUTUAL EXCLUSION SEMAPHORE
 *
 * Description: This function signals a mutual exclusion semaphore
 *
 * Arguments  : pevent              is a pointer to the event control block associated with the desired
 *                                  mutex.
 *
 * Returns    : OS_NO_ERR               The call was successful and the mutex was signaled.
 *              OS_ERR_EVENT_TYPE       If you didn't pass a pointer to a mutex
 *              OS_ERR_PEVENT_NULL      'pevent' is a NULL pointer
 *              OS_ERR_POST_ISR         Attempted to post from an ISR (not valid for MUTEXes)
 *              OS_ERR_NOT_MUTEX_OWNER  The task that did the post is NOT the owner of the MUTEX.
 *              OS_ERR_PIP_LOWER        If the priority of the new task that owns the Mutex is
 *                                      HIGHER (i.e. a lower number) than the PIP.  This error
 *                                      indicates that you did not set the PIP higher (lower
 *                                      number) than ALL the tasks that compete for the Mutex.
 *                                      Unfortunately, this is something that could not be
 *                                      detected when the Mutex is created because we don't know
 *                                      what tasks will be using the Mutex.
 *********************************************************************************************************
 */

INT8U  OSMutexPost(OS_EVENT *pevent)
{
    INT8U pip;                                        /* Priority inheritance priority                 */
    INT8U prio;

#if OS_CRITICAL_METHOD == 3                           /* Allocate storage for CPU status register      */
    OS_CPU_SR cpu_sr = 0;
#endif



    if (OSIntNesting > 0)                             /* See if called from ISR ...                    */
    {
        return OS_ERR_POST_ISR;                       /* ... can't POST mutex from an ISR              */
    }
#if OS_ARG_CHK_EN > 0
    if (pevent == (OS_EVENT*)0)                       /* Validate 'pevent'                             */
    {
        return OS_ERR_PEVENT_NULL;
    }
#endif
    if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX)   /* Validate event block type                     */
    {
        return OS_ERR_EVENT_TYPE;
    }
    OS_ENTER_CRITICAL();
    pip  = (INT8U)(pevent->OSEventCnt >> 8);          /* Get priority inheritance priority of mutex    */
    prio = (INT8U)(pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8);  /* Get owner's original priority      */
    if (OSTCBCur != (OS_TCB*)pevent->OSEventPtr)      /* See if posting task owns the MUTEX            */
    {
        OS_EXIT_CRITICAL();
        return OS_ERR_NOT_MUTEX_OWNER;
    }
    if (OSTCBCur->OSTCBPrio == pip)                   /* Did we have to raise current task's priority? */
    {
        OSMutex_RdyAtPrio(OSTCBCur, prio);            /* Restore the task's original priority          */
    }
    OSTCBPrioTbl[pip] = (OS_TCB*)1;                   /* Reserve table entry                           */
    if (pevent->OSEventGrp != 0)                      /* Any task waiting for the mutex?               */
    {                                                 /* Yes, Make HPT waiting for mutex ready         */
        prio                = OS_EventTaskRdy(pevent, (void*)0, OS_STAT_MUTEX);
        pevent->OSEventCnt &= OS_MUTEX_KEEP_UPPER_8;  /*      Save priority of mutex's new owner       */
        pevent->OSEventCnt |= prio;
        pevent->OSEventPtr  = OSTCBPrioTbl[prio];     /*      Link to new mutex owner's OS_TCB         */
        if (prio <= pip)                              /*      PIP 'must' have a SMALLER prio ...       */
        {
            OS_EXIT_CRITICAL();                       /*      ... than current task!                   */
            OS_Sched();                               /*      Find highest priority task ready to run  */
            return OS_ERR_PIP_LOWER;
        }
        else
        {
            OS_EXIT_CRITICAL();
            OS_Sched();                               /*      Find highest priority task ready to run  */
            return OS_NO_ERR;
        }
    }
    pevent->OSEventCnt |= OS_MUTEX_AVAILABLE;         /* No,  Mutex is now available                   */
    pevent->OSEventPtr  = (void*)0;
    OS_EXIT_CRITICAL();
    return OS_NO_ERR;
}
/*$PAGE*/
/*
 *********************************************************************************************************
 *                                     QUERY A MUTUAL EXCLUSION SEMAPHORE
 *
 * Description: This function obtains information about a mutex
 *
 * Arguments  : pevent          is a pointer to the event control block associated with the desired mutex
 *
 *              p_mutex_data    is a pointer to a structure that will contain information about the mutex
 *
 * Returns    : OS_NO_ERR            The call was successful and the message was sent
 *              OS_ERR_QUERY_ISR     If you called this function from an ISR
 *              OS_ERR_PEVENT_NULL   If 'pevent'       is a NULL pointer
 *              OS_ERR_PDATA_NULL    If 'p_mutex_data' is a NULL pointer
 *              OS_ERR_EVENT_TYPE    If you are attempting to obtain data from a non mutex.
 *********************************************************************************************************
 */

#if OS_MUTEX_QUERY_EN > 0
INT8U  OSMutexQuery(OS_EVENT *pevent, OS_MUTEX_DATA *p_mutex_data)
{
    INT8U i;

#if OS_LOWEST_PRIO <= 63
    INT8U     *psrc;
    INT8U     *pdest;
#else
    INT16U    *psrc;
    INT16U    *pdest;
#endif
#if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
    OS_CPU_SR cpu_sr = 0;
#endif



    if (OSIntNesting > 0)                                  /* See if called from ISR ...               */
    {
        return OS_ERR_QUERY_ISR;                           /* ... can't QUERY mutex from an ISR        */
    }
#if OS_ARG_CHK_EN > 0
    if (pevent == (OS_EVENT*)0)                            /* Validate 'pevent'                        */
    {
        return OS_ERR_PEVENT_NULL;
    }
    if (p_mutex_data == (OS_MUTEX_DATA*)0)                 /* Validate 'p_mutex_data'                  */
    {
        return OS_ERR_PDATA_NULL;
    }
#endif
    if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX)        /* Validate event block type                */
    {
        return OS_ERR_EVENT_TYPE;
    }
    OS_ENTER_CRITICAL();
    p_mutex_data->OSMutexPIP  = (INT8U)(pevent->OSEventCnt >> 8);
    p_mutex_data->OSOwnerPrio = (INT8U)(pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8);
    if (p_mutex_data->OSOwnerPrio == 0xFF)
    {
        p_mutex_data->OSValue = 1;
    }
    else
    {
        p_mutex_data->OSValue = 0;
    }
    p_mutex_data->OSEventGrp  = pevent->OSEventGrp;        /* Copy wait list                           */
    psrc                      = &pevent->OSEventTbl[0];
    pdest                     = &p_mutex_data->OSEventTbl[0];
    for (i = 0; i < OS_EVENT_TBL_SIZE; i++)
    {
        *pdest++ = *psrc++;
    }
    OS_EXIT_CRITICAL();
    return OS_NO_ERR;
}
#endif                                                     /* OS_MUTEX_QUERY_EN                        */

/*$PAGE*/
/*
 *********************************************************************************************************
 *                                RESTORE A TASK BACK TO ITS ORIGINAL PRIORITY
 *
 * Description: This function makes a task ready at the specified priority
 *
 * Arguments  : ptcb            is a pointer to OS_TCB of the task to make ready
 *
 *              prio            is the desired priority
 *
 * Returns    : none
 *********************************************************************************************************
 */

static void  OSMutex_RdyAtPrio(OS_TCB *ptcb, INT8U prio)
{
    INT8U y;


    y            =  ptcb->OSTCBY;                          /* Remove owner from ready list at 'pip'    */
    OSRdyTbl[y] &= ~ptcb->OSTCBBitX;
    if (OSRdyTbl[y] == 0)
    {
        OSRdyGrp &= ~ptcb->OSTCBBitY;
    }
    ptcb->OSTCBPrio         = prio;
#if OS_LOWEST_PRIO <= 63
    ptcb->OSTCBY            = (INT8U)((prio >> 3) & 0x07);
    ptcb->OSTCBX            = (INT8U)(prio & 0x07);
    ptcb->OSTCBBitY         = (INT8U)(1 << ptcb->OSTCBY);
    ptcb->OSTCBBitX         = (INT8U)(1 << ptcb->OSTCBX);
#else
    ptcb->OSTCBY            = (INT8U)((prio >> 4) & 0x0F);
    ptcb->OSTCBX            = (INT8U)(prio & 0x0F);
    ptcb->OSTCBBitY         = (INT16U)(1 << ptcb->OSTCBY);
    ptcb->OSTCBBitX         = (INT16U)(1 << ptcb->OSTCBX);
#endif
    OSRdyGrp               |= ptcb->OSTCBBitY;             /* Make task ready at original priority     */
    OSRdyTbl[ptcb->OSTCBY] |= ptcb->OSTCBBitX;
    OSTCBPrioTbl[prio]      = ptcb;
}


#endif                                                     /* OS_MUTEX_EN                              */
